The long-term solution
Interim beach works at Semaphore and Largs Bay
Semaphore South dune restoration
Securing the future of our coastline
What is the current state of our metropolitan beaches?
Some parts of the Adelaide beaches are experiencing significant sand loss and erosion of the sand dune system. The sand along Adelaide’s coast naturally moves northward, by the wind and waves. This causes sand to build up on our northern beaches such as Semaphore, and causes sand loss and erosion along our southern and central coast such as West Beach and Henley Beach South. The State Government manages the metropolitan coastline to enable the community to enjoy sandy beaches. Works to move sand has occurred across the metropolitan beach system for more than 40 years.
West Beach has had serious and ongoing erosion for a number of years. At present, beach levels at West Beach and Henley Beach south are lower than at any other time since records began.
From Henley Beach to the north, the beaches are generally in good condition as the sand lost from southern beaches drifts north.
Sand continues to accumulate in Largs Bay, with wide dunes from around the Semaphore jetty northwards.
The beaches in the southern part of the coast (from Glenelg to Kingston Park) are generally stable because of successful beach management. The pipeline from Glenelg to Kingston Park currently pumps approximately 100,000m3 of sand successfully each year.
Read an article from InDaily ‘Shifting sands – why SA pays for an endless cycle of beach replenishment’
What has been the impact of our eroded beaches?
The erosion at West Beach has had a number of impacts. Immediately north of the boat harbour the dunes have receded many metres, relying on regular recycling of sand from further north to manage the erosion.
Further north, the beach at the West Beach Surf Life Saving club has been mostly eroded and the clubhouse, coast park and car park rely on a seawall for protection.
At the northern end of the seawall, the erosion has lowered the beach so that the beach access ramp is sometimes closed. The loss of dunes in this area has placed assets at risk, and is requiring regular beach replenishment with sand from Semaphore to maintain protection levels.
The erosion has progressed to affect Henley Beach South, with much of the sand dunes in front of the seawall being affected.
What is the DHI report? What does it say?
In 2017, a coastal processes modelling study was commissioned by the Department for Environment and Water, the Coast Protection Board, the City of Charles Sturt and West Beach Parks to better understand the coastal processes at West Beach and to examine alternative management options. This was needed because of the ongoing loss of sand each year at West Beach.
External consultants DHI completed a
report in 2018.
The research undertaken by DHI has shown that the sand loss at West Beach (the section of coastline running north from the West Beach boat harbor at West Beach Parks to the Torrens Outlet) is significant, and greater than previously estimated.
The report made it clear that even if current management activities were maintained, erosion will continue around West Beach and Henley Beach South, and progressively move north.
The report tested out three alternative scenarios for managing the beach and dune erosion at West Beach, with their results modelled. All three options involve beach replenishment, and varied by bringing in differing amounts of sand over different timescales.
During the course of the study, the scope was amended to expand the analysis of beach profiles along the entire system from Kingston Park to Largs Bay, to enable a better understanding of the influence of management of adjacent beaches on West Beach and vice versa. This expanded analysis also provides insight into the management of the entire Adelaide beach system.
The long-term solution
What is the government doing to address the problems in the long term?
In June 2019, the government announced a $48.4 million investment to the metropolitan coast over four years. This consists of $20 million for additional sand including approximately 500,000 cubic metres (m³) of newly sourced sand; and $28.4 million for the completion of a sand recycling pipeline from Semaphore to West Beach, as well as sand dune restoration and revegetation in partnership with local councils and coastal community groups.
The beach replenishment will put sand on our most vulnerable and eroded beaches including West Beach and Henley Beach South, with benefits to other beaches as sand naturally moves northward.
The announcement has been informed by
research completed in 2018 by external consultants DHI on behalf of the Department for Environment and Water, the Coast Protection Board, the City of Charles Sturt and West Beach Parks.
When will it start? When will the pipeline be built?
In 2019/20 and 2020/21, we’ll be increasing our beach replenishment to West Beach and Henley Beach South each year to match current rates of loss and stabilise and maintain the beaches and dunes in the short term. (See:
Interim beach works at Semaphore and Largs Bay)
Then in 2021/22, a large scale replenishment using sand from an external source (outside of the Adelaide beach system) is planned to be delivered. This will raise the beach levels and boost sand dune buffers at West Beach and Henley Beach South with benefits to other beaches as sand moves northward.
Following the project planning phase (including detailed designs, engineering, community consultation and approvals), the pipeline is planned for construction in 2021/22, with the pipeline operational by end 2022/23.
Where will the sand come from and why do we need an ‘external’ sand source?
There is a limited amount of sand in Adelaide’s beach system. To find a suitable external sand source for the large scale beach replenishment, we will investigate offshore sand deposits as well as some land-based sources. See '
Why can’t external sand be brought in now?'
Sand will also continue to be moved from Adelaide’s northern beaches (including the Semaphore South breakwater and from between the Semaphore and Largs Bay jetties) in 2019/20 and 2020/21. This is being done to restore sand that is currently being lost from West Beach and Henley Beach South each year while external sand is sourced and the sand recycling pipeline is constructed.
Watch the video to learn more about how we manage Adelaide’s beaches
The Semaphore South breakwater (pictured at the far end of the beach in photo)
is the primary source of sand to replenish Adelaide’s eroding southern beaches.
Sand is also being moved from the beach between the Semaphore and Largs Bay jetties.
This photo was taken two weeks after sand was collected in November 2019.
How will this impact our northern beaches, like Semaphore?
Management of the entire metropolitan coast needs to be adaptive and flexible. Our beaches are constantly changing and sand is naturally moved northward by the wind and waves, which causes sand to build up on our northern beaches, such as Semaphore, but causes erosion along our southern and central coast such as Seacliff, Brighton and Henley Beach.
A sustainable approach to managing our beaches involves recycling sand from areas of where sand builds up to areas of loss. Investigations have taken place to see if sand in other northern beaches is suitable to use for beach replenishment while the pipeline is built and before sand from an external source is available.
Sand is being collected periodically from beaches between the Semaphore jetty and Largs Bay jetty, which have large sand accumulations, to supplement the amount of sand collected from the Semaphore South breakwater.
(See ‘ Why is sand being collected between the Semaphore and Largs Bay jetties?’)
Why are we building a sand recycling pipeline and where will it be located?
A sand recycling pipeline from Semaphore to West Beach will provide an efficient means to recycle sand. This will provide a long term solution to keeping sand on our most exposed and vulnerable beaches.
Pipelines provide more flexibility in managing our beaches – with multiple intake and discharge locations allowing sand to be picked up where there is an accumulation and delivered to locations most at need across the beach system. We have seen this success with the Glenelg to Kingston Park pipeline, which currently pumps approximately 100,000m
3 of sand each year.
Another major benefit of the pipeline is reducing the reliance on trucks to move sand, making it safer for the community, as well as reducing noise, congestion and the impact of trucks on roads.
The exact location of the pipeline and how it will be built will be determined in the planning and design period starting in 2019-20.
You can find out more about the existing sand recycling pipeline and how it works, including technical information
What impacts will building the pipeline have on our beaches and dunes?
We will minimise the impacts as much as possible during construction. The community will be kept informed and have opportunities to find out more in the coming months.
There will be short-term impacts from construction. Disturbance of existing dunes and ecological communities will be avoided or minimised.
The works will recycle sand each year to maintain critical dune buffers. This provides the base for dune restoration for the foreshore at West Beach and Henley Beach South in particular. The government will partner with the community and councils to revegetate the foreshore and develop stable sand dunes with vibrant ecological communities.
There will be some impact for many residents and beach goers as these works are undertaken. We will keep the community informed during all phases of the projects.
There will be opportunities to find out more in the coming months, including through
public events and information sessions. Public notices will be published in local papers and we will also meet with local community groups.
A community reference group is being formed to involve community stakeholder groups in the project.
We will work in partnership with local councils and coastal community groups on sand dune restoration and revegetation works.
Register your interest to learn more at a community bus tour and see the Glenelg to Kingston Park pipeline in action.
Sign up to receive updates contact us.
Don’t we already have a pipeline?
two existing underground sand recycling pipelines - Glenelg to Kingston Park and Torrens Outlet to the West Beach dunes - were completed in 2013 to transfer a slurry of sand and seawater from beaches where sand is building up, to the eroding beaches further south.
The pipeline from Glenelg to Kingston Park currently pumps approximately 100,000m
3 of sand successfully each year.
This project will extend the pipeline from the northern beaches, to connect to the existing infrastructure at Torrens Outlet to the West Beach dunes.
What happened to the sand moved to West Beach over the last year?
The West Beach area has been eroding since the 1960s and has received many hundreds of thousands of cubic metres of sand to manage the area over the years. Previously it was estimated that sand depleted from the West Beach area was about 50,000 m³/year. Most of this is through natural northward movement, with very little lost offshore.
The new research undertaken by DHI estimates that annual depletion is actually between two and three times that rate, meaning that even when current replenishment activities are taken into account there is a net annual loss of approximately 60,000 m³.
Windy weather and strong waves have caused erosion to continue at West Beach, and when beaches are replenished with sand it is normal for some of it to be washed away during the next storm. If the replenishment sand wasn’t there, then West Beach would be even more eroded and exposed.
Much of the sand that is washed offshore during storms is moved back onshore during calmer periods, so it is not wasted. This sand will also help maintain beaches as it drifts naturally to the north.
Adding sand to the Adelaide beach system benefits more than just West Beach, it also ensures there is more sand to flow between the beaches and be recycled.
Why aren't structures like groynes built to try to reduce the natural drift of sand northward?
Structures of the size required to have an impact are very expensive to construct. These areas would then require large volumes of sand to be brought in from an external source to “pre-fill” them. This pre-filling with external sand is essential otherwise the coast to the north of each structure would be eroded.
In addition, the experience with structures on the Adelaide coast and elsewhere in South Australia is they also trap large quantities of beach-cast seagrass, which has an impact on the usability of the beaches and increases management costs.
When factoring in these aspects, the sustainable approach to managing our beaches involves recycling sand from areas where sand builds up to areas of loss. This means the protection of Adelaide’s beaches can be achieved without negative impacts from structures, which would tend to interrupt our long sandy beaches..
By building a structure or structures like groynes and breakwaters that slow sand movement along the coast, the area in the vicinity of the trapped sand can be protected. However, the coast to the north (down-drift) of the structure will then be starved of sand unless the area is replenished.
An example of the use of structures along the beach in Japan.
Options involving the construction of hard engineering structures to re-orientate the West Beach shoreline were considered by DHI and included offshore breakwaters and headland control structures. A range of risks and disadvantages were identified with these options. The DHI report does not model any management options that use structures to retain sand on the beaches.
Why does Seacliff beach look so good? How has dune restoration helped?
During the 1980s and 90s, the Seacliff and Brighton coast was suffering from severe erosion that threatened the foreshore. To address this a large scale beach replenishment with sand sourced externally was undertaken. This formed and stabilised the dunes, with the active involvement of local community dune care groups and volunteers. The local council supported these efforts with ongoing restoration involving drift fencing trapping sand to control sand drift, access control, weed removal and re-vegetation. The operation of the sand recycling pipeline from 2013 onwards has further stabilised this part of the coast and allowed dunes to flourish.
What is being done to help beaches outside of Adelaide?
Local councils play a critical role in protecting regional assets from coastal hazards and maintaining coastal areas for all South Australians and tourists. The state government has committed an additional
$4 million over 4 years to regional coasts to repair, restore and sustain them in partnership with local councils. This support responds to the increasing demand for coastal protection infrastructure to address hazards like flooding and erosion.
The program is open to councils with a particular focus on the outer metro and regional areas.
Read the latest works update
The department is regularly meeting with community representatives and council to help guide the Semaphore sand movement works.
Why is sand being collected between the Semaphore and Largs Bay jetties?
The state government’s long term strategy to manage the erosion at West Beach and Henley Beach South includes a commitment to match the rate of sand loss at these beaches by moving sand in the short term while new sand is sourced from outside of the Adelaide beach system and a sand recycling pipeline from Semaphore to West Beach is built.
(See ‘ When will it start? When will the pipeline be built? ’).
Due to the natural northward movement, sand builds up at Semaphore. Much is captured at the Semaphore South breakwater. Sand has also accumulated at beaches between the Semaphore and Largs Bay jetties. Sand now needs to be collected from the beach between the Semaphore jetty and Largs Bay jetty to supplement the amount of sand collected from the Semaphore South breakwater.
Technical and environmental information Why isn’t sand collected from the beaches further north, like North Haven?
Historically, sand at the northern end of Largs Bay has proven to be unsuitable for replenishing beaches further south on the Adelaide coast as it is finer and would wash away much more quickly. The
most recent analysis
shows that while suitable sand can be found to just north of Largs Bay jetty, the build-up of sand beyond that would not be suitable for replenishing West Beach or its adjacent beaches.
The properties of Adelaide’s natural beach sand has been thoroughly investigated to inform beach management decisions and help identify suitable sources of sand for beach replenishment.
What will the likely impacts to the dunes between Semaphore and Largs Bay jetties be?
The dunes in between the Semaphore and Largs Bay jetties vary from 80 metres wide to over 100 metres wide, and sand will be sourced from the beach where the dunes are wider.
Any indication of foredune erosion at this location would be closely monitored to ensure the foreshore remains protected and the wider dune system maintained.
It is expected that this impact will be short-term until Semaphore beach naturally replenishes with sand that naturally moves north again, enabling the foredune to rebuild.
Semaphore beach two weeks after the sand was collected in November 2019.
How will the impacts to the dunes be managed?
We acknowledge the great work that dune care groups do to look after our beaches and their extensive local knowledge of the dunes. We will work with them to minimise the impacts to our beaches and dunes during this time. There will be opportunities in the future for community groups to partner with the local council for dune care grants to further improve the coastal biodiversity.
We will continue to monitor the beaches and dunes to ensure the foreshore remains protected.
In March 2020, the department engaged independent ecologists to undertake a vegetation survey to assess and map the flora along 5km length of coast between Semaphore Surf Life Saving Club and Strathfield Terrace, Largs North. The field assessment includes gathering information about native species present, weed species present and their cover category, native plant life forms, native/exotic understorey biomass and tree health.This information will be used to help inform future works including
dune restoration at Semaphore South. What about impacts to the dunes to the south of the breakwater?
Since October 2018 approximately 100,000 cubic metres of sand (about the equivalent of 40 Olympic sized swimming pools) has been moved from the Semaphore South breakwater to West Beach and Henley Beach South.
The dunes at Semaphore Park have built up since the Semaphore South breakwater was built in 2005. Some erosion of dunes may result from sand sourcing. There will remain more than enough sand in these dunes to continue to protect the foreshore and development at Semaphore Park.
Have environmental impacts been considered?
Semaphore has been used as a sand source area at various times since the 1970s and has naturally replenished without causing significant environmental impacts.
The approach for managing Adelaide’s beaches is based on expert advice underpinned by decades of data collected, including current and historical survey information on beach profiles and independent technical reports.
At the location between the Semaphore and Largs Bay jetties, the government’s beach profile data indicates that there is sufficient dune volume buffer and the area will steadily build up again through natural processes. A team of environmental specialists monitor and assess Adelaide’s beaches regularly.
The Department for Environment and Water works with Birdlife Australia to ensure any impacts to shorebirds are avoided or minimised.
Securing the future of our coast project will improve dune biodiversity in the longer-term along Adelaide’s coast by stabilising the beaches and dunes with a steady supply of replenishment sand and through partnerships with council and community groups.
See also 'Has an assessment of the dune vegetation been done?' Once the pipeline is built, how much sand will be sourced from Semaphore?
Once operational, the sand recycling pipeline will be used to source sand from areas where sand is built up to replenish areas that are eroding further south. Analysis of the beach profiles conducted by the Department for Environment and Water will provide information on where sand is accreting or eroding and inform these decisions. The Semaphore South breakwater, designed to trap sand for replenishment, will continue to be a primary source of sand.
Average natural sand movement northwards along the coast is approximately 100,000 cubic metres each year, and this will need to be matched by replenishment of West Beach at the southern end of the pipeline pumping system. The volumes of sand eroding and building up along the beach system will vary from year to year, depending on the shape and height of the sea bed, the weather and storms and this will influence the amount of sand which needs to be collected for replenishment.
Community safety is a priority. Safety signage is in place on the beaches during works.
The community and beach users are asked to please take extra care on the beaches while the works are underway and adhere to all safety signage and flagging in place during operations. Qualified contractors are employed for works. The successful contractor is required to develop a job safety plan and a thorough risk management plan. This includes safe management between the work and members of the public.
Traffic control complies with relevant Australian Standards and Code of Practice. Traffic controllers and/or signage is provided where necessary.
We also liaise with Surf Life Saving SA and the Semaphore Life Saving Club regarding beach safety.
Can I access the beach during the works?
The beach remains open during works.
The community and beach users are asked to:
Take extra care on the beaches, streets and surrounding area during works. Adhere to safety signs and directions.
Why isn’t dredging or a barge used to move sand instead?
Shifting sand by dredging it onto a barge would be severely limited by weather conditions, increasing the cost and increasing the time taken to conduct beach works. The amount of sand needed to match the rate of loss from West Beach and Henley Beach South could not be moved efficiently and cost-effectively with a dredge.
Why can’t external sand be brought in now?
There is a limited amount of sand in Adelaide’s beach system and to find a suitable external sand source for the large scale beach replenishment will take time. We will investigate offshore sand deposits as well as some land-based sources.
These investigations and other planning and approvals are required before the external sand is delivered. The large scale replenishment using sand from an external source is planned to be delivered in 2021/22. View the project timeline
here. Has the department looked at the work done to manage beaches in other areas?
Beach management strategies vary across Australia and internationally due to differences in coastal processes, climate and landscape. The approach for managing Adelaide’ beaches is based on expert advice underpinned by decades of data collected, review and assessment of methods used around the world, consideration of the issues specific to Adelaide’s beaches, and including current and historical survey information on beach profiles and independent technical reports.
A community reference group is being formed to help improve awareness of the
Securing the Future our Coast project and management of Adelaide beaches.
The department has also established a working group including representatives from the community (Semaphore South residents, Save our Shores: Semaphore Largs and the Semaphore Largs Dunes Group) and the City of Port Adelaide Enfield relating to sand movement works at Semaphore.
What engagement with local businesses has there been?
The government liaise with local businesses, who may be impacted by beach works. We work to minimise disturbance to the community as much as possible by not operating during school holidays or on weekends.
What is being done to manage the erosion to the north of the Semaphore South breakwater?
The area immediately north of the Semaphore South breakwater (from approximately Hart Street to Noonies Cafe) was adversely impacted by a severe storm in 2016 which resulted in the loss of the dune and its vegetation.
This area has been periodically replenished with sand from the Semaphore jetty.
Works are needed to restore the dunes and protect the area from further damage by storms.
Initial discussions between the Department for Environment and Water, City of Port Adelaide Enfield and community representatives have focussed on how best to rebuild the eroded dunes and stabilise the area with vegetation.
What is proposed to restore the dunes?
Recent sand testing shows that the sand in the location to the north of the Largs Bay jetty (to approximately Strathfield Terrace at Largs North) is compatible with Semaphore South sand and could be used to replenish the eroded dunes at Semaphore South.
No decision has yet been made on this proposal and
community input is now being sought.
How much sand is proposed to be taken?
The proposal is to use in the order of 25,000 to 28,000 cubic metres (m³) of sand from north of the Largs Bay jetty to rebuild the Semaphore South dunes.
How do you know that the sand to the north of the Largs Bay jetty is suitable?
Historically, sand at the northern end of Largs Bay has proven to be unsuitable for replenishing beaches further south on the Adelaide coast as it is finer than the native beach sand and would wash away more quickly. The
most recent sand sampling analysis (2019)
indicated that sand in the area immediately north of Largs Bay jetty has become coarser over time and is now suitable for replenishing Semaphore South.
Large volumes of coarse sand from external sources were added to the southern beaches in the 1990s. It is possible that this sand has now moved northwards into this section of the coast. The testing showed that sand north of Largs Bay remains unsuitable for replenishing beaches further to the south.
When could the work be done?
Dune restoration works could be done in May/June 2020.
This timing would also ensure that a buffer is in place in the area before winter when storms causing further erosion are more likely.
How will the sand be stabilised once it has been moved to Semaphore South?
The sand will be shaped to match the normal dune profile along Adelaide’s metropolitan coast (i.e. raised foredune area and lower rear dune area). Stabilisation would then use the following well established methods based on drift net fencing and revegetation (refer for example to the
Tasmanian Coastal Works Manual for further information).
Standard drift net fences, as used extensively in other council areas, would be erected along the dune, parallel to the beach. The drift fences help to trap windblown sand coming from the beach and frontal dune and contribute to the growth of the dunes both vertically and horizontally.
A small scale trial using beach cast seagrass wrack in the stabilisation works is being considered. If suitable accumulations of beach-cast seagrass wrack are available nearby at the time of works, it would be spread as cover mulch over an area of dune that will be planted. This is expected to help reduce the windblown sand coming from the dune and add some organic matter to assist plant growth. However, it is recognised that beach cast seagrass wrack provides an important ecological function and any trial will only proceed following consultation with Birdlife Australia representatives.
If available and feasible, sprinkler irrigation may be installed on risers. This will improve with plant establishment and help in mitigating wind-blown sand.
Ongoing weed control and further plantings will occur in subsequent years.
These techniques have been used with great success to reestablish dunes on Adelaide’s southern beaches, such as at Seacliff and South Brighton (example pictured below).
Dune restoration examples at South Brighton. Photos courtesy City of Holdfast Bay
Could seaweed bales be used to help stabilise the newly placed sand?
Not as part of the proposed trial. Baling seagrass is labour-intensive and beach cast seagrass wrack plays an important ecological function in the coastal environment.
If there are accumulations of wrack nearby at the time of works, consideration is being given to conducting a small scale trial of using the wrack as a cover mulch to assist with the revegetation works.
Is this a one-off project or will it be a regular occurrence?
The proposal to reestablish the Semaphore South dunes using sand from north of the Largs Bay jetty is a one-off trial project. However, as has occurred in the past, the seaward part of the Semaphore South dunes will erode over time and will require periodic replenishment with smaller amounts of sand to maintain the foredune area that is directly exposed to coastal processes. The sand used to replenish Semaphore South has previously been moved back from the area around Semaphore jetty.
Testing during 2019 showed that sand to the north of Largs Bay jetty is suitable for replenishing the Semaphore South area. Further analysis during the trial would confirm whether this area is another possible location from which sand can periodically be moved back to replenish the Semaphore South dunes.
How would this impact the dunes north of the Largs Bay jetty?
The approach for managing Adelaide’s beaches is based on expert advice underpinned by decades of collected data, including current and historical survey information on beach profiles and independent technical reports. A team of environmental specialists monitor and assess Adelaide’s beaches regularly. Annual beach surveys are undertaken along the coast to measure the beach profiles and assess if there is a sufficient dune volume buffer in the area.
The government has assessed that any environmental impacts on the coastline north of Largs Bay jetty as a result of the proposed removal of the volume of sand required to rebuild the Semaphore South dunes would be minor. The stabilisation and revegetation of the Semaphore South dunes would create significant environmental benefits associated with improved biodiversity outcomes.
At the location north of the Largs Bay jetty, the government’s beach profile data indicates that there is sufficient dune volume buffer to allow removal of the sand required to rebuild the Semaphore South dunes. Based on previous experience and monitoring of areas where sand has been collected, the impact on the dunes of removing sand from the intertidal zone as part of the trial is expected to be minimal. The area will steadily build up again through natural processes.
The department engaged independent ecologists to undertake a March 2020 vegetation survey to assess and map the flora along the 5km length of coast between Semaphore Surf Life Saving Club and Strathfield Terrace.
See ‘ Has an assessment of the dune vegetation been done?’
This baseline information will inform species selection for the proposed planting of the restored Semaphore South dunes, will enable any impacts of the proposed trial to be monitored, and will inform future works.
The field assessment includes gathering information about native species present, weed species present and their cover category, native plant life forms, native/exotic understory biomass, tree health, etc. Incidental fauna observations will also be recorded.
Is there a long-term solution planned for the Semaphore South erosion problem?
The proposal to rebuild and stabilise the Semaphore South dunes using sand from north of the Largs Bay jetty will not negate the need for ongoing periodic replenishment of the Semaphore South area.
The foredune area would still be subject to coastal processes, including erosion during storm events, and it is expected that periodic replenishment (on a smaller scale) will continue to be required on a periodic basis to replenish the foredune.
Semaphore South has previously been replenished using sand from the Semaphore jetty area. The proposed trial using sand from north of Largs Bay jetty would inform whether this is an additional option for consideration as part of the long term management of the Semaphore South coastline.
Who can I contact for more information?
For enquiries contact the Department for Environment and Water on 8124 4928 or email